Field of the Invention
The present teaching relates to an image recording apparatus configured to make a sheet on which an image is recorded by a recording unit contact with a contact member, thereby preventing the sheet from floating.
Description of the Related Art
There is conventionally known an ink-jet recording apparatus which records an image by discharging ink droplets onto a sheet, such as a recording sheet, from nozzles provided for a recording unit. The ink-jet recording apparatus includes a platen (a sheet support member), which is disposed to face the recording unit and supports the sheet. The recording unit is slidably supported by a pair of guide rails, which is provided on upstream and downstream sides in a sheet conveyance direction to extend in a width direction orthogonal to the sheet conveyance direction.
When the sheet is conveyed on the platen, the recording unit selectively discharges ink droplets on the sheet on the platen while moving on the pair of guide rails in the width direction orthogonal to the sheet conveyance direction. Accordingly, the image is recorded on the sheet.
The ink-jet recording apparatus may have such a phenomenon (cockling) that a part, of the sheet, to which the ink is adhering, swells and floats from the platen. The cockling causes the part of the sheet floating from the platen to make contact with the recording unit and/or a guide member which guides the sheet to the platen. This could lead to a defective image, a paper jam, etc.
In order to solve the above problem, there has been conventionally known an image recording apparatus, which includes contact members in a guide rail disposed on the upstream side in a sheet conveyance direction and is configured to press a sheet conveyed on a platen against the platen. Each of the contact members includes an attachment part, a curved part, and a flat-plate contact part. The attachment part is brought into contact with the lower surface of the guide rail. The curved part extends from the attachment part toward the downstream side in the sheet conveyance direction in a state of being curved downward. The flat-plate contact part extends from the lower end of the curved part toward the downstream side in the sheet conveyance direction.
The attachment parts of the contact members are attached to the guide rail so that four engaging parts are engaged with the guide rail. Two of the four engaging parts are provided as a pair on the upstream side, and the other two engaging parts are provided as a pair on the downstream side. The engaging parts pass through openings penetrating the guide rail in an up-down direction to be engaged with the upper surface of the guide rail.
The curved parts hang down from the attachment parts. The contact parts are pushed upward by being brought into contact with a sheet conveyed. Then, the reaction force from the contact parts presses the sheet against the platen, thereby preventing the sheet from floating from the platen.
In the image recording apparatus, the engaging parts of the contact members are engaged with the guide rail with clearance (backlash) intervening therebetween. This allows the contact parts to move upward when the contact parts are brought into contact with the sheet. When the contact parts are not brought into contact with the sheet, the contact parts are inclined so that its front ends on the downstream side in the sheet conveyance direction are positioned on the lowermost side.
In the above structure or configuration, when the contact parts are pushed upward by being brought into contact with the sheet, the attachment parts rotate around the engaging parts provided, as the pair, on the upstream side in the sheet conveyance direction. Then, when the contact parts are pushed upward to a position where appropriate pressing force is applied to the sheet, the guide rail regulates the attachment parts not to move the contact parts from this position.
As described above, the guide rail regulates the attachment parts to position the contact parts. The pressing force applied from the contact parts to the sheet is also influenced by the weight of the curved parts and contact parts. Thus, it is difficult to perform adjustments of positions of the contact parts in the up-down direction in which the appropriate pressing force, which fails to change the position of the sheet, is applied to the sheet.
Further, the above image recording apparatus may have the following structure or configuration. Namely, when the paper jam of the sheet on the platen occurs in the image recording apparatus, the sheet is pulled toward a direction opposite to the sheet conveyance direction in order to clear the paper jam. In this case, the contact parts are inclined so that the front ends thereof are positioned on the lowermost side, and thus the front ends of the contact parts may pierce the sheet pulled toward the direction opposite to the sheet conveyance direction. This could lead to the damage of the sheet or the worsening of the paper jam.
The present teaching has been made in view of the abovementioned circumstances, and an object of the present teaching is to provide an image recording apparatus which allows contact parts of contact members to make contact appropriately with a sheet on which an image is recorded by a recording unit.